Tasmania in September 2010: Cold, snow to low levels, flooding and huge waves 

Though few temperature and rainfall records were broken in Tasmania during September, there were many interesting weather events. Huge waves were generated by a deep low on the 16th, snow fell to low levels on several days and heavy rain in the north caused flooding on the 4th. There were several very cold days and nights, and few mild ones.

  • Rainfall above average except for the upper east
  • Temperatures below average overall
  • Westerlies with cold fronts for much of the month

Huge waves

The waverider buoy off Cape Sorell on Tasmania’s west coast registered an 18.4 metre wave at about 11 am on the 16th. This approaches the record wave of 19.8 metres measured by a similar buoy operated by CSIRO in July 1985. The peak was a single wave, but for most of the 16th waves at the buoy were averaging over 8 metres. The observers at Maatsuyker Island just off Tasmania’s south coast reported an exceptional 11 metre swell, and at Cape Bruny 10 metres was reported. The huge waves were generated by strong winds around a deep low pressure system over the Southern Ocean south of Tasmania as a cold front swept across the state. The same system brought damaging winds, rain, hail and snow, with road closures, building damage and failed power lines reported across the state. Wind gusts reached 148 km/h at Maatsuyker Island and 141 km/h at Cape Bruny. A few days later the same system brought extreme weather to New Zealand.

Heavy rain and flooding

Heavy rain fell across most of Tasmania on the 4th as a deepening low pressure system approached from the northwest then crossed the state overnight. By 9 am, 15 to 25 mm had fallen in the northwest with light falls elsewhere. The rain continued during the day, with a further 81 mm at Mount Victoria, 75 mm at Mount Barrow and 63 mm at Mount Read during the next 24 hours, causing flooding of most rivers across northern Tasmania. In total, over 50 mm fell in most of the north, west and far south, with near 100 mm on higher ground in the northeast. 

Mostly wet overall

After the heavy rain on the 4th, the weather pattern over Tasmania was nearly always westerly with cold fronts crossing the state regularly. From the 10th it rained every day in the west, and showers extended to most other areas with each front. This meant it was wetter than usual in all but the upper east. Monthly totals graded markedly across the state, from a high of 549 mm at Mount Read in the west to just 18 mm at Swansea in the east. Some areas had nearly double the September average, and Lunawanna (on Bruny Island) had its wettest September since 1984.

Cold days and nights with snow to low levels

There were several very cold days and nights during September. Mount Wellington had the two coldest days for the state so far this year, not rising above -2.2 C on the 28th and -2.1 C on the 29th. Liawenee fell to -7.9 C on the morning of the 7th, equalling the coldest temperature recorded during winter. Liawenee also fell below -7 C on the 3rd and 8th: never before has it had so many nights this cold in September. Other sites had their coldest September day or coldest night in many years including Dover, which had its coldest September morning on the 8th, and many sites in the south on the 15th. The cold was accompanied by snowfalls to low levels on the 15-16th and 28-29th, something that is uncommon at this time of year and contrasted with a relatively mild winter.

For the whole month, daytime temperatures were mostly one to three degrees cooler than usual in the west and south and slightly cooler than usual elsewhere, while minima were near average. It was the coldest September since at least 2003 for most sites, and Strathgordon had its coolest mean maximum temperature on record for September.

In with the cold weather there were a few days and nights that were warmer than usual, generally when fronts were crossing the state overnight or it was fine during the day. The 20th was especially warm in the north and east with temperatures around 20 C. Swansea reached 21.7 C on this day, the warmest temperature in Tasmania for the month, and Devonport reached 19.6 C, its highest September temperature in 19 years of record. The warmest nights were the 5th, 25th and 27th, when temperatures didn't drop below 10 C in many areas.

Hobart: wet and windy with many cold nights

It was a wet and windy September in Hobart. A total of 88 mm of rain was recorded for the month, less than the 133 mm that fell last year but still 35 mm more than the long-term average. As with most of Tasmania, the heaviest rain fell on the 4th when 27 mm was recorded in 24 hours. After the westerlies kicked in around the 10th, most days in Hobart were windier than usual, especially on the 15th to 18th and 27-28th. There were three days when gusts exceeded 90 km/h, an equal record for September.

There were many cold nights in Hobart with the temperature dropping below 4 C ten times, nearly double the normal for September and something that hasn't happened for over 15 years. The coldest temperature was 1.7 C on the 7th, Hobart's coldest September morning since 1995. There were also a number of cold days, the coldest being 10.5 C on the 28th (although on the 16th the temperature was below 6 C for much of the afternoon). The cold was tempered by some warm periods from the 9th to the 12th and 23rd to 26th, so that over the whole month mean temperatures were near normal. The warmest day was 18.9 C on the 26th and the warmest night was 11.9 C on the 25th.

Temperatures for the year to date in Hobart are still very warm: the mean daily maximum temperature of 17.9 C for this period is the highest in over 120 years of record.

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Extremes in September 2010
Hottest day 21.7 C at Swansea Post Office on the 20th
Warmest days on average 16.3 C at Bicheno (Council Depot)
Coolest days on average 3.3 C at Mount Read
Coldest day -2.2 C at Mount Wellington on the 28th
Coldest night -7.9 C at Liawenee on the 7th
Coolest nights on average -1.8 C at Mount Wellington
Warmest nights on average 9.0 C at Swan Island
Warmest night 12.6 C at Scamander on the 25th
Warmest on average overall 11.9 C at Eddystone Point
Coolest on average overall0.9 C at Mount Wellington
Wettest overall 549.2 mm at Mount Read
Driest overall 18.4 mm at Swansea Post Office
Wettest day 81.4 mm at Mount Victoria (Una Plain) on the 5th
Highest wind gust 148 km/h at Maatsuyker Island Lighthouse on the 15th

Maps

ObservedAnomalyDecile rank
Total
rainfall
Map of Rainfall totals Map of Percentage of normal rainfall Map of Rainfall deciles
Mean
daily
maximum
temperatures
Map of Mean maximum temperature Map of Anomaly in mean maximum temperature Map of Decile rank of mean maximum temperature
Mean
daily
minimum
temperatures
Map of Mean minimum temperature Map of Anomaly in mean minimum temperature Map of Decile rank of mean minimum temperature

Click on a map to show it full size in a pop-up window



Highest total September rainfall for at least 20 years

Total rainfall
for September 2010 (mm)
Most recent September
at least this wet
Years since
wetter
Average for
September
Lunawanna 138.4 149.8 in 1984 25 71.2


Record lowest September mean daily maximum temperature

Mean daily maximum
temperature
for September 2010 (C)
Previous coolest
for September
Years of
record
Average for
September
Strathgordon Village 9.3 9.5 in 1970 28 11.5

Lowest September mean daily maximum temperature for at least 20 years
Mean daily maximum
temperature
for September 2010 (C)
Most recent September
at least this cool
Years since
cooler
Average for
September
Maatsuyker Island Lighthouse 10.2 =10.2 in 1970 40 12.2
Butlers Gorge 8.1 7.9 in 1969 24 10.1



Record lowest September temperature

Lowest temperature
in September 2010 (C)
Previous coolest
for September
Years of
record
Average for
September
Dover -2.1 on the 8th -1.0 on the 9th in 1992 21 4.9





Summary statistics for September 2010
Maximum temperatures
for September
(C)
Minimum temperatures
for September
(C)
Rainfall
for September
(millimetres)
Mean for
September
2010
Diff
from
average
Highest for
September
2010
Mean for
September
2010
Diff
from
average
Lowest for
September
2010
Total for
September
2010
Average
for
September
Rank of
September
2010
Fraction of
September
average
Northern (district 91)
Bridport (Sea View Villas) 14.2 -0.5 19.0 21st 6.1 -0.7 0.6 29th 78.0 76.5 average 102%
Burnie (Round Hill) 14.2 -0.1 19.4 21st 7.4 +0.6 2.3 29th 96.6 87.7 average 110%
Cape Grim BAPS 12.6 -0.8 14.7 12th 8.2 -0.4 4.3 3rd 100.8 77.0 high 131%
Cressy Research Station 14.1 -0.6 19.3 20th 4.0 +0.1 -2.5 8th 57.0 63.8 average 89%
Devonport Airport 14.5 +0.4 19.6 20th 6.4 +0.4 -0.1 30th 85.2 74.9 average 114%
Launceston (Ti Tree Bend) 15.3 -0.2 19.4 20th 5.1 -0.1 -0.6 30th 78.0 67.1 average 116%
Launceston Airport 14.2   18.9 20th 3.7   -2.5 30th 55.0
Low Head 13.5 -0.5 16.8 21st 8.5 +0.1 2.3 30th 86.4 66.7 high 130%
Luncheon Hill (Forestry) 11.0 -1.3 15.2 21st 4.7 -0.7 1.1 29th 192.2 179.6 average 107%
Marrawah     15.1 21st 7.3 -0.1 3.5 3rd 121.4 105.8 average 115%
Scottsdale (West Minstone Road) 13.5 -0.7 18.3 20th 4.5 -0.2 -2.2 30th 128.0 99.5 high 129%
Sheffield School Farm 12.4 -0.7 19.3 20th 4.4 -0.3 -0.9 30th 127.6 128.6 average 99%
Smithton Aerodrome 13.8 -1.0 16.7 21st 5.9 -0.4 -0.6 2nd 116.2 107.1 average 108%
Wynyard Airport 14.4 +0.1 19.2 20th 5.8 +0.9 -0.1 14th 138.2 95.9 high 144%
East Coast (district 92)
Bicheno (Council Depot) 16.3 +0.2 20.0 25th 7.1 -0.3 1.7 8th 21.8 44.4 low 49%
Eddystone Point 16.0 +1.2 20.5 20th 7.9 -0.1 2.1 29th 51.0 63.5 average 80%
Fingal (Legge Street) 14.5 -0.8 20.4 20th 3.0 -0.3 -3.2 30th 22.2 49.6 low 45%
Friendly Beaches 15.9 -0.8 21.3 20th 7.1 -0.4 1.3 8th 27.8 38.0 average 73%
Lake Leake (Elizabeth River) 10.7 -0.6 17.3 20th 1.7 -0.3 -3.8 2nd 53.2 71.0 average 75%
Maria Island (Point Lesueur) 14.4   18.0 25th 7.8   3.2 29th 47.4
Orford (Aubin Court) 14.7 -1.0 19.6 26th 5.7 +0.2 -0.4 8th 54.8 51.9 average 106%
Scamander 16.1 -0.2 19.3 25th 6.5 -0.2 1.2 14th 21.7 54.0 low 40%
St Helens Aerodrome 15.8   21.1 20th 6.4   0.7 14th 21.8
Swan Island 14.0   16.8 21st 9.0   4.0 30th 41.4
Swansea Post Office 16.1 +0.1 21.7 20th 6.3 +0.5 -0.7 8th 18.4 40.9 low 45%
Midlands (district 93)
Ross (The Boulevards) 13.9 -0.5 20.4 20th 3.4 -0.3 -4.6 7th 34.6 53.7 average 64%
Southeast (district 94)
Campania (Kincora) 14.6 -1.7 19.2 12th 5.5 +0.3 -1.5 7th 66.2 50.8 high 130%
Cape Bruny (Cape Bruny) 12.6 -1.8 17.3 9th 6.3 -1.2 2.5 28th 131.4 70.8 v high 186%
Cape Bruny Lighthouse 12.3 -0.9 16.5 9th 6.4 -0.6 2.3 28th 142.8 81.2 v high 176%
Dover 12.8 -1.8 17.6 9th 4.7 -0.2 -2.1 8th 146.0 84.2 high 173%
Geeveston (Cemetery Road) 12.8 -2.0 16.1 25th 5.3 +0.9 -1.2 3rd 152.8 93.4 high 164%
Grove (Research Station) 13.5   17.4 12th 4.1   -3.1 3rd 157.0
Hobart (Ellerslie Road) 14.8 -0.3 18.9 26th 6.6 +0.2 1.7 7th 88.2 53.4 high 165%
Hobart Airport 14.7 -0.6 19.1 12th 6.3 +0.3 0.5 8th 61.4 42.4 high 145%
Maatsuyker Island Lighthouse 10.2 -2.0 13.0 12th 6.3 -0.5 2.6 14th 136.4 109.5 high 125%
Melton Mowbray (North Stockman) 12.8 -1.8 17.5 26th 4.3 -0.1 -2.6 7th 62.2 55.3 average 112%
Mount Wellington 3.8 -0.5 8.1 26th -1.8 -0.5 -5.6 28th
Tasman Island 11.2   16.6 12th 6.0   0.8 17th 114.8
Tunnack Fire Station 11.3 -1.2 16.5 26th 2.8 -0.5 -4.3 7th 86.8 68.0 high 128%
Derwent Valley (district 95)
Bushy Park (Bushy Park Estates) 14.3 -1.1 18.5 26th 4.2 +0.3 -3.5 8th 106.8 54.3 v high 197%
Maydena Post Office 11.0 -2.7 16.0 21st 3.1 -0.3 -2.0 3rd 179.2 142.2 high 126%
Ouse Fire Station 13.7 -2.1 17.6 12th 4.6 +0.9 -3.9 8th 103.6 75.7 high 137%
Tarraleah Village 9.1 -2.1 13.1 21st 2.0 +0.2 -3.0 3rd 160.9 120.3 high 134%
Central Plateau (district 96)
Butlers Gorge 8.1 -2.0 13.2 7th 1.5 +0.6 -3.8 8th 246.2 169.1 high 146%
Lake St Clair National Park 8.5 -1.5 12.6 7th 0.9 +0.1 -4.9 8th 272.4 216.2 average 126%
Liawenee 7.4   15.6 20th -0.8   -7.9 7th 70.4 127.4 low 55%
West Coast (district 97)
Hartz Mountain (Keoghs Pimple) 5.9 -2.8 11.8 7th 0.7 -1.1 -2.6 28th 140.2 102.0 high 137%
Mount Read 3.3 -2.2 7.7 4th -0.6 -1.0 -4.4 29th 549.2 341.3 high 161%
Scotts Peak Dam 9.7 -2.6 15.9 21st 3.2 -1.1 -1.6 8th 310.2 219.3 high 141%
Strahan Aerodrome 12.7 -1.6 15.3 21st 5.9 -0.3 -0.6 3rd 223.8 140.3 high 160%
Strathgordon Village 9.3 -2.2 13.7 21st 3.9 -0.5 -0.5 3rd 462.3 281.1 v high 164%
Warra 8.9   12.8 9th 2.4   -2.7 7th 309.8
King Island (district 98)
King Island Airport 13.7 -0.9 15.5 25th 8.3 0.0 3.7 2nd 74.0 88.3 average 84%
Flinders Island (district 99)
Flinders Island Airport 14.2 -0.9 16.6 4th 8.3 +0.8 -0.1 8th 37.6 63.9 low 59%
Hogan Island 13.2   15.4 12th 8.8   5.3 28th 38.4
Antarctica and Macquarie Island (district 300)
Macquarie Island 4.0 -1.4 6.6 12th -0.2 -1.7 -6.8 25th 94.0 74.6 high 126%


Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Tasmania using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 10 am on Friday 1 October 2010. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Media
(03) 9669 4057
Enquiries